The present invention relates to a static random-access memory (SRAM), and more specifically, to saving data in a low power state in the SRAM, such that the subsequent reading of the saved data results in reduced dissipation of dynamic power.
In SRAM, one major component of overall dynamic power consumption is the read operation in which a majority of the read bit lines (which may include local and/or global bit lines) are discharged and precharged during the evaluation and precharge stages of a read cycle. Whether a particular bit line discharges or not depends on the state of the bit array cell being accessed. If the bit array cell being accessed stores a particular value (e.g., a high power state), then the dynamic evaluation results in bit lines being discharged from their precharged states, and then subsequently requiring power to restore them to their precharged states. If, on the other hand, the bit array cell being accessed stores the opposite value (e.g., a low power state), then less power is consumed as there is no switching activity in the dynamic path from the array cell to the readout circuitry.